1. Field of the Invention
The present invention relates to a strain imparting device for a grain oriented electrical steel sheet. More particularly, it relates to a strain imparting device for producing a low watt loss electrical steel sheet by imparting small linear deformation regions, hereinafter referred to as minute strain, to surfaces of an oriented electrical steel sheet.
2. Description of the Related Art
In the past, to reduce the watt loss of the electrical steel sheet (hereinafter referred to as steel sheet), a process for imparting minute-strain to a surface of a steel sheet has been used. For example, Japanese Unexamined patent publication No. 56-36341 discloses that linear strain is imparted to a surface of a steel sheet while rotating a hard globular rotator. Further, Japanese Unexamined patent publication No. 55-92227 discloses that linear strain is imparted to a steel sheet by pressing a strain imparting block, against a surface of steel sheet within which block a retractable shaft having rotating-pressing rings at the ends thereof is transversly provided.
However, above-mentioned processes are disadvantageous in that the constitutions thereof are composite, the life of a device used in the process is not sufficient, and since it is necessary to stop movement of the steel sheet during the process, the processes is not efficient.